Republican presidential candidates are voicing strong opposition in the wake of Friday's deadly attacks in Paris to President Barack Obama's plan to allow 10,000 Syrian refugees to enter the United States over the next year.

Their criticism comes as Republican governors say they will block Syrian refugees from entering their states, citing concerns over terrorism.

Obama, meanwhile, has stood by the plan.

"As president, my first priority is the safety of the American people, and that's why even as we accept more refugees, including Syrians, we do so only after subjecting them to rigorous screening and security checks," Obama said Monday after the G-20 summit in Turkey.

Obama also criticized Republicans for arguing that the U.S. should only admit Christian Syrians.

"That's shameful," Obama said. "That's not American. That's not who we are. We don't have religious tests to our compassion."

Here's where some of the 2016 GOP field stands on refugees as of Monday:

Ben Carson

Carson, who is currently leading the GOP field in some polls, said Friday that the U.S. should block refugees from the Middle East.

"If we're going to be bringing 200,000 people over here from that region -- if I were one of the leaders of the global jihadist movement and I didn't infiltrate that group of people with my people, that would be almost malpractice," he told reporters in Orlando, Florida.

On Sunday, he further criticized Obama's plan to allow 10,000 Syrian refugees to enter the U.S., saying it would be a "huge mistake" to do so.

"To bring them here under these circumstances is a suspension of intellect," Carson said on Fox News Sunday.

Marco Rubio

The senator from Florida, who previously said he was "open" to taking in refugees, said on ABC's "This Week" that "we won't be able to take more refugees" from Syria.

"It’s not that we don’t want to," he said. "It's that we can't."

Ted Cruz

Back in October, Cruz said allowing Syrian refugees into the U.S. would be "nothing short of crazy," warning that Islamic State terrorists could be among those entering the country.

"It would be the height of foolishness to bring in tens of thousands of people including jihadists that are coming here to murder innocent Americans," he said.

The U.S. senator from Texas has stood by that stance since Friday's attacks, calling Obama's plan "lunacy" and calling for a block against Muslim refugees. He also claimed that Christian refugees pose "no meaningful risk" of terrorism.

Donald Trump

The business mogul described Syrian refugees as a "Trojan horse" on Monday.

"We have no idea who these people are, we are the worst when it comes to paperwork," Trump told CNBC. "This could be one of the great Trojan horses. ... We cannot let them into this country, period."

Rand Paul

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Paul warned Saturday that the U.S. and Europe "have to be very careful about bringing refugees to our country that might attack us.”

"People talk about the large influx of people leaving the Middle East, going to Europe and some of them wanting to go to the United States, that it may not be a benign thing to accept so many tens of thousands of people coming from the Middle East because many of them actually wish us harm," he said.

The Kentucky senator also criticized 2016 rival Marco Rubio for opposing an amendment Paul added to the 2013 immigration bill. The amendment would have bolstered screenings for individuals entering the country.

"I think that was a mistake, not only for the bill, but also for our national security," Paul said.

Jeb Bush

Bush, the former governor of Florida, said the U.S. should focus on helping Christian refugees for the time being.

"There should be really thorough screening [of refugees coming to the U.S.] and we should focus on creating safe havens for refugees in Syria rather than bringing them all the way across to the United States," Bush said Monday. "But I do think there is a special important need to make sure that Christians from Syria are being protected because they are being slaughtered in the country and but for us who? Who would take care of the number of Christians that right now are completely displaced?"

Carly Fiorina

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Carly Fiorina is upset President Barack Obama had said the Islamic State had been "contained."

In September, the former Hewlett-Packard CEO argued against opening the U.S. to Syrian refugees, voicing concern over the threat of terrorism.

After Friday's attacks, Fiorina claimed Obama is accepting refugees "unilaterally," and criticized the president for saying the Islamic State had been "contained."

"I am angry. I am angry that just yesterday morning, our president, against all evidence, declared ISIS contained and took a victory lap," she said. "ISIS is not a 'JV team,' Mr. President, they are not contained, they are at our shores and they measure their victory in body count."

John Kasich

The Ohio governor said Monday that the U.S. should reject Syrian refugees but stopped short of saying he wouldn't allow them in his state.

"There is no way that we can put any of our people at risk," Kasich said Monday on Fox Business Network. "Should anybody come in here before the end of the year? The answer to that should be no. We should not jeopardize our people. And so it's not just an issue of the heart. It's also an issue of the head."

"I join President Obama in offering my deepest condolences to all those wounded and to the families who lost loved ones in today&rsquo;s terrorist attacks in Paris.&nbsp; It&rsquo;s heartbreaking. Outrageous. The American people understand and share the pain the people of Paris are going through. As these tragic events unfold, the investigation continues, and we learn all of the details of what&rsquo;s happened, the United States stands ready to support the French government and the people of Paris.&nbsp; And, as we&rsquo;ve done before, in the face of dangers and threats, we will look out for one another.&nbsp; We will stand together.&nbsp; We will never bow.&nbsp; We will never break.&nbsp; That&rsquo;s the character of our two nations.&nbsp; We are bound by timeless democratic values that the cowardice and perverse ideologues of extremist networks can never match, wherever they are. Such savagery can&nbsp; never threaten who we are. We will respond. We will overcome. We will endure."